The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the electronics industry utilized various methods and circuits to protect batteries, such as lithium ion (Li-Ion) batteries, from unpredictable voltages that would be applied to the battery by a battery charging controller. Typically the output of the battery charging controller was regulated, however, if the controller were incorrectly connected excessive-voltages were applied to the battery. One example of such a battery charging controller was the Max4840 manufactured by Maxim Integrated Products of Sunnyvale Calif. The Max4840 used an N-channel MOS transistor which was disabled if the battery charging voltage exceeded about six volts. One problem with the prior controllers was that the battery was not protected against reverse or negative voltages. The negative voltages detrimentally affected the battery and could also damage the charging controller.
Accordingly, it is desirable to have a battery protection circuit that protects the battery from both positive over voltages and negative under voltages.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor.